I am doing a project on cold gas thrusters and have seen a couple of graphs relating chamber pressure against mass flow rate. I can't seem to find the equation that relates these two parameters to produce this asymptotic 1/ln |x| looking graph.

Image 1 [https://www.researchgate.net/publication/323629454_Influence_of_combustion_chamber_pressure_on_injector_performance]

enter image description here

Another similar graph is a screenshot from a YouTube video (link provided below, at 12:06 minutes).

Image 2 [https://www.youtube.com/watch?v=9ar2kTgFQsI]

enter image description here

If anyone could help locate this equation for me, it would be much appreciated. Thanks :)

  • 1
    $\begingroup$ Please edit your question to show the graph you are asking about in a way that does not involve watching a video. If you are not yet allowed to post pictures, post a link and someone will edit it in for you. $\endgroup$ May 16, 2021 at 11:10
  • $\begingroup$ I've edited the question! $\endgroup$ May 16, 2021 at 12:09
  • $\begingroup$ Thanks, looks good. One more thing, you should always provide a link or at least site your sources (where you got the graphs from). Welcome to space stack exchange! $\endgroup$ May 16, 2021 at 12:20
  • $\begingroup$ Thanks :) I've provided all the references above each image! $\endgroup$ May 16, 2021 at 13:22
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    $\begingroup$ That all said, looking at the charts this seems to be more an exercise of calculating fluid flow from the tank to the combustion chamber. You may have an easier time just looking up flow through a pipe or orifice. The chances are that these plots have been produced from something quite simple though where specific assumptions have been made about various parameters. $\endgroup$
    – Puffin
    May 16, 2021 at 21:56


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